<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div id="app">
      <h1>{{name}}</h1>
    </div>
  </body>
</html>
<script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
  const vm = new Vue({
    el: "#app",
    data: {
      name: "沈峤",
      obj: {
        age: 18,
        hobby: "唐先生",
      },
    },
    watch: {
      name(newVal, oldVal) {
        console.log("newVal====" + newVal);
        console.log("oldVal====" + oldVal);
      },
      //   obj: {
      //     handler(newVal) {
      //       console.log(newVal);
      //     },
      //     deep: true,
      //   },
      "obj.age"(newVal, oldVal) {
        console.log("newVal====" + newVal);
        console.log("oldVal====" + oldVal);
      },
    },
  });
</script>
